1 Field of the Invention
This invention relates to a device for performing such post-processing as sorting and stapling of sheets fed out from an image forming apparatus such as a copying machine to which this device is joined, and more particularly to a sheet post-handling device having a stapling system and driving system assembled rationally within side frames of the device, thereby to make the device compact.
2. Description of the Prior Art
There has been generally used a sheet post-handling device provided with a stapling unit in order to automatically performing post-processing such as sorting and stapling of sheets undergoing image processing in an image forming apparatus such as a copying machine and a printer. The sheet post-handling device coupled to a sheet discharge part of the image forming apparatus is provided with mechanisms for placing in order, sorting, aligning and stapling the sheets, and/or arranging the pages of the sheets properly on one or more sheet processing trays.
The sheet processing tray for stacking the whole sheets thereon to process the sheets calls for a large space for accommodating the sheets entirely, resulting in a large overall size of the device. Specifically when handling the sheet of large size, the increase in size and weight of the device entails a disadvantage such that the device inevitably turns out to be awkward to handle. Such a disadvantage may be somewhat surmounted by such a device as disclosed in U.S. Pat. No. 5,385,340, in which only one end part of sheets is supported inside, holding the remaining part outside when being stapled.
However, there is a limit in reducing the size of the sheet handling device, provided an operating mechanism including systems for transferring a sheet to be processed, controlling driving components and transmitting drivng power to the driving components is not made compact. The sheet post-handling device of this type cannot be made compact as long as it employs complicated operating mechanism relying on a plurality of driving motors and intricate power transmission means. Moreover, the conventional sheet post-handling device has a disadvantage of being complicated in control and working motion thereof and susceptible to mechanical troubles and/or failure to transfer the sheet.
Although the sheet post-handling device of this type is desired to be easy to handle in loading a stapling unit with staples for binding the sheets and maintaining the stapling unit, the conventional device is disadvantageous in that the stapling unit immovably fixed on the device must be located at a position renderng the staple-loading work difficult in case where an image forming apparatus to which the sheet post-handling device is coupled is set at a narrow place or inconvenient situation. Under certain circumstances, the heavy device must be moved whenever the stapling unit is loaded with the staples. This turns out to be a very troublesome chore.
An object of the present invention is to provide a sheet post-handling device having a simple sheet post-handling mechanism including a stapling unit and a driving mechanism including a sheet transferring system and a motion transmission system are rationally incorporated within a device frame, thereby making the device compact.
Another object of the present invention is to provide a sheet post-handling device capable of being made compact by using a single driving motor, a simple driving mechanism for transferring sheets and applying driving power and a simple control system, and assuredly and efficiently performing desired sheet post-handling operation by controlling the driving mechanism with exquisite timing.
Still another object of the present invention is to provide a sheet post-handling device capable of being easily operated and handled without requiring spatial restriction by permitting an operator to easily approach and handle a stapling unit incorporated in the device in loading the stapling unit with staples and effecting maintenance of the device.
To attain the objects described above aocording to this invention, there is provided a sheet post-handling device comprising first and second side frames, a sheet processing tray for supporting sheets to be processed, which is defined by the side frames, a stapling unit for stapling the sheets, which is mounted within the first side frame at one side portion of the sheet processing tray, a sheet transferring system for transferring the sheet from a sheet reception part to a sheet discharge part through the sheet processing tray, and a driving system for driving the sheet transferring system, which is mounted in the second side frame and includes a driving power source and driving elements.
This sheet post-handling device is joined to a sheet discharge portion of an image forming apparatus such as a copying machine, to which a sheet is fed from the image forming apparatus after subjecting the sheet to image processing in the image forming apparatus. In the case of stapling the sheets fed from the image forming apparatus by using the stapling unit in the sheet post-handling device, the sheets traveling from the sheet reception part toward the sheet discharge part is moved backward to the sheet processing tray. When sending a prescribed number of sheets onto the sheet processing tray, the sheets are pressed laterally against the first side frame by a sheet aligning member to align the sheets, and then, stapled by the stapling unit. The stapled sheets are sent out to an external tray through the sheet discharge part.
The sheet transferring system indudes sheet introducing rollers located at the sheet reception part, sheet feeding rollers arranged on a sheet transfer passage extending from the sheet reception part to the sheet discharge part, an elastically deformable feeding ring of a large diameter being inscribed with one of the aforesaid feeding rollers so as to send forward the sheet placed on the sheet transfer passage and move backward the sheet placed on the sheet processing tray, a paddle for causing the sheet traveling forward along the sheet transfer passage to be moved backward to the sheet processing tray, and paired sheet discharge rollers for sending out the sheets stapled on the sheet processing tray to the external tray.
As the sheet is fed from the image forming apparatus, the sheet introducing rollers, feeding rolers and feeding ring are constantly rotated to forward the sheet along the sheet transfer passage.
In the case of stapling the sheets, the sheet traveling along the sheet transfer passage is moved backward onto the sheet processing tray by rotating the paddle in the reverse direction when the tail end of the sheet passes through the feeding rollers. The paddle, which is selectively rotated by the feeding rollers, makes one rotation in the reverse direction to move the sheet backward. As the sheets thus fed onto the sheet processing tray come up to the prescribed number, the stapling unit is operated to staple the sheets on the tray into a bundle. Upon completion of the stapling, the sheets thus stapled are discharged in a bundle to the external tray through the sheet discharge part by rotating the sheet discharge rollers.
The driving system for operating the sheet transferring system indudes a driving motor for rotating the sheet infroducing rollers and feeding ring, and a timing gear wheel which is selectively rotated by the feeding ring. A motion transmission means through which the rotation of the timing gear wheel is transmitted to the sheet discharge rollers may be incorporated within the first side frame.
The timing gear wheel to be meshed with an intermediate gear has a non-toothed part in which no gear tooth is formed, so as to selectively transmit the rotation of the feeding rollers through the intermediate gear. The timing gear wheel is provided with a cam for rocking a rocking arm supporting one of the sheet discharge rollers, which is in separable contact with the other sheet discharge rollers. The paired sheet discharge rollers come in contact with each other in a sheet forwarding mode for sending out the sheet to the discharge part, and are out of contact therewith in a sheet aligning mode for moving the sheet backward.
The driving system for transferring the sheet is operated by a single motor, so that the mechanism for driving and controlling the system can be incorporated rationally within one side frame, and consequently, the device can be made compact.
Other and further objects of this invention will become obvious upon an understanding of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.